The present invention is related to the field of audio players and, more particularly, to a system for automatically shutting off portable audio players.
Some people have found increasing popularity in the use of portable audio players. The relatively small packaging combined with relatively large data storage has enamored some people to not only carry portable audio players on their person, but to use portable audio players to replace some larger home audio equipment. Home use of portable audio players may be attributed to developments in portable audio player accessories. Some accessories include docking stations or hubs that may serve as an intermediary between the portable audio player and a speaker system. In some cases, the docking stations include playing portable audio player files as only one of a number of functions. For instance, some docking stations may also include FM/AM tuners, a compact disc player, etc. Thus, the docking station and portable audio player may have entirely independent power sources.
In some cases, a person may power up both the docking station and portable audio player to listen to music files from the portable audio player. Subsequently, content with having heard enough music from the portable audio player, the person may shut off the docking station yet forget to power off the portable audio player leaving it to run and expend its battery capacity.
It is known in the art to shut off a device when input has ceased for a predetermined amount of time. For example, computer monitors may include a sleep mechanism to power off the video output when a user has delayed too long in using interfaces in connection with the computer. However, some portable audio players may be designed to continuously play music files regardless of the last time a user interfaced with the device's input mechanisms.
It is also known in the art to monitor the impedance on speaker lines for determining if an audio signal is present. Impedance may depend on the uniformity of connections among speakers. When measuring impedance, it may be difficult to evaluate the variance of impedance between speakers where some speaker wires have less stable connections or there are differences in wire qualities.
Hence, there is a need for a system for automatic shutoff of portable audio players.